1. Field of the Invention
Embodiments of the invention generally relate to methods and apparatus for attachment of a secondary tool handling device to a primary tool handling device. More specifically, the embodiments relate to methods and apparatus for attachment of a secondary elevator to a primary elevator on a drilling rig used in the oil and gas industry.
2. Description of the Related Art
In a drilling operation or rig work-over operation, a tubular handling system is utilized to support tubular members or circular tools, such as casing, tubing, drill pipe, or sucker rods, and position and/or lift or lower the tubular members relative to a wellbore or platform. A conventional drilling or work-over rig typically includes a primary elevator that supports the tubular members for the positioning and/or lifting and lowering. The elevator is typically coupled to a travelling block (i.e., a support structure) by links above the wellbore, which allows the elevator to move up and down when handling the tubular members. The elevator most commonly used in the operations described above may be an elevator suitable for safely handling multiple joints of tubular members, such as a casing elevator, although other elevators may be utilized as the primary elevator.
During these operations it is sometimes necessary or practical to use a secondary elevator that is different than the primary elevator. For example, the secondary elevator may be suitable for safely handling a single joint of a tubular member, such as a single joint elevator. Traditionally, the secondary elevator is either attached directly to the lower link ears of a standard elevator. However, the lower link ears are not load-rated, which creates safety risks. Alternatively, the secondary elevator is attached to the travelling block providing support to the primary elevator. However, this attachment method requires an independent, extended support sling that is routed from the travelling block, down the elevator links and past the primary elevator. This method requires the use of various attachment mechanisms to secure the sling to the primary elevator and links. The use of a sling and other attachment mechanisms in this manner causes instability of the secondary elevator, and creates a potential safety risk as the sling and other attachment mechanisms can get caught in other rigging gear. In addition, these attachment mechanisms represent additional potential for dropped objects.
What is needed is a method and apparatus for safely attaching a secondary elevator to a primary elevator that does not require the use of extended slings and includes a load-rated attachment point and mechanism for attachment of the secondary elevator.